We should keep in mind that apparent unknown chambers were detected by a Japanese team, using some kind of low-invasion method, circa 1980. The team was kicked out and banned from the plateau.
I don't doubt that there's nothing left to be found, and that the burial chamber (which was open to ancient tourists for centuries, before being resealed) was looted long, long ago.
Its just sort of depressing how much of the ancient world has been lost to looting, natural disasters, amd the type of fires that wiped out the Alexandrian library.